This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -3 |
| 3 | 24 |
| 4 | -226 |
| 5 | 2791 |
| 6 | -42467 |
| 7 | 761826 |
| 8 | -15714798 |
| 9 | 366401751 |
| 10 | -9528266885 |
| 11 | 273439284005 |
| 12 | -8584541521286 |
| 13 | 292695692569785 |
| 14 | -10771202678289501 |
| 15 | 425538242701632216 |
| 16 | -17964593967281888258 |
| 17 | 807094224863059707077 |
| 18 | -38449142619220645357810 |
| 19 | 1935991142823285710574298 |